Functionalized Chromans and Isochromans via a Diastereoselective Pd(0)-Catalyzed Carboiodination

A diastereoselective approach to isochromans and chromans via Pd(0)-catalyzed carboiodination is reported. The transformations using this methodology display excellent yields and diastereoselectivities as well as broad functional group compatibility. The selectivity observed in these cyclizations, forming isochroman or chroman targets, is postulated to originate from the minimization of A^1,2 strain and axial–axial interactions, respectively. This method has also been used to highlight the concept of reversible oxidative addition to carbon–iodine bonds in polyiodinated substrates.